I'm inclined to say no. There are 7,000 fixed seats + the berm and the Brewers only draw on average 5,200 at Maryvale. God forbid there by a sellout, i'd bet the secondary market is teeming with alternatives. Ive been out here for 13 years now and I think ive maybe seen 1 or 2 sellouts in that time. Simply put, Maryvale doesnt sell out. The Royals and Giants will draw decent crowds but with a plethora of lawn seating you should be fine. Also the larger crowds seem to be the week before you are planning to attend, when spring break is in full swing. The last week of March the crowds start to dwindle